Green Nanofabrication @ Leidenfrost Condition
Nanotechnology applications revolutionize our daily life in the new millennium. It has enormous promising applications that considerably influences the whole world. Things like consumer goods, nanofiltration, nanoelectronics, nanomedicine, aerospace, defense, energy, environment, and all fields of economy are deeply affected by nanotechnology. Thus, there should be some innovative methods to meet the growing requirement of nanobased products. These methods need to be simple to handle, environmental-friendly, energy efficient, and low cost. Leidenfrost effect can be reflected in our daily life. In our home kitchen, while cooking for example, if a drop of water touches a hot surface which is at a temperature much higher than the boiling point of water, the lower part of the drop is evaporated and the water levitates on its own vapor film. In this thesis, the Leidenfrost drop has been introduced as a water-based green chemical reactor for simultaneous synthesis and self-organization of nanostructures. An important contribution of this work is in exploring the origin and mechanism of the nanofabrication at Leidenfrost condition. It turns out that these conditions are based upon overheated and charged nature of the droplet. Moreover, this thesis demonstrates the synthesis of structured nanoparticles, their assembly in the form of 3D nanocoating on complex objects, the design and development of nanoporous metal suspension and the foam structures. Through the nanofabrication process, some exemplar applications are represented such as plasmonic wideband superabsorber, which could be a good candidate for solar energy harvesting as well as a superhydrophilic and thermal resistive metal-polymer hybrid foam. Furthermore, it turns out that this new green strategy provides the possibility to produce nanopowder with customized morphology thereby affecting the thermal emissivity in addition to many other functions. This water-based, one step, cost effective and eco-friendly approach does not contain any hazardous organics, capping agents or coordination compounds that can contaminate the product and consequently complicate its application. The synthesized nanomaterials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared (IR) thermography, X-ray diffraction (XRD) and ultraviolet-visible spectroscopy (UV-Vis).